Set almost entirely within the confines of a New York apartment, Carnage revolves around the discourse between two sets of couples: the Cowans (Kate Winslet and Christoph Waltz) and the Longstreets (Jodie Foster and John C. Reilly). They have never met before, but the Cowans have come to visit because their son hit the Longstreets' son in the face with a stick, breaking several of the boy's teeth. Believing it to be the civilized thing to do, the four parents draft a letter explaining the incident, then try to arrange a date when the two boys can meet up and discuss their differences in a more civil manner than they have in the past. Despite their best efforts to leave, the Cowans find themselves drawn back into the apartment again and again, and as they spend more time together, the underlying tension between the couples begins to bubble over into outright anger, resentment and bitterness.
Adapted from Yasmina Reza's play "The God of Carnage" by Reza and Polanski, Carnage remains true to its theatrical origins by keeping the action confined to one location - apart from a prologue and an epilogue, both of which take place in the park where the confrontation between the two boys occurred - and by forcing its four leads to be constantly in each others presence. Whilst Polanski has demonstrated a tremendous ability to mine menace and tension from people being trapped together in his earlier films, such as in his 1965 debut Knife In The Water, which explores similar territory but does so on a boat, and the long tradition of the theatre of menace, many examples of which created terrifying works from trapping a small number of characters in one location, here the tension fails to appear.
This is not a fault of the cast, all of whom do fantastic work - with Waltz being the clear standout - but with the overall tone of the film, which aims to be a dark comedy but which fatally isn't all that funny. Polanski brings a suffocating seriousness to the work that undermines its attempt to highlight the hypocrisy of society and civil discourse, turning what should be acidic comedy into leaden drama. The lines themselves still have real bite to them, and it's easy to see why they would have worked on stage, but the pacing of the film prevents them from having the full impact that they should. The relentless pacing of the film is meant to make everything seem claustrophobic, but it winds up being tiring more than anything else, and at 80 minutes the film barely feels as if it has started by the time it ends.
Whilst its speed kills much of the comedy, it also prevents Carnage from delving into the issues that it raises. The script introduces little details then sets them aside like unexploded bombs, waiting for the right moment to detonate: some peach cobbler, some warm Coke, a story about a hamster, all represent the falling pebbles that are meant to trigger a devastating avalanche, but the avalanche never truly comes. We see flashes of the hostility beneath the calming mask of civility that each of the characters puts on, and which gradually slips as they get increasingly drunker, but it feels like something else is meant to happen. It's very reminiscent of Who's Afraid of Virginia Woolf, in that respect, but for all the talk of its characters letting loose and finally saying what they mean, they and the film hold back far more than the characters in that earlier, superior work. There's a promise of something truly awful happening that is never fulfilled, and the resulting anti-climax is doubly worse because not only is it frustrating, but it also fails to offer any meaningful comment on the build up of that expectation. (Anti-climax itself is, of course, not a bad thing, as any one who has watched The Sopranos will attest, but anti-climax without comment is just bad storytelling.)
Carnage stirs up all these ideas about what society really means and whether or not taking part in it represents an elevation of our species or a gross denial of it, and whilst those ideas may be provocative, albeit in a very superficial way, the lack of significant results ultimately prevents Carnage from working as either comedy or drama. The lack of any emotional or comedic pay off in turn undermines the thematic concerns of the work, since it's hard to really care about what any of the characters are saying if there's nothing interesting about the characters themselves.